The present invention is directed to a process for preparing heterocyclic sulfonyl chloride compounds by chloroxidation of di(heterocyclyl) disulfide compounds.
The preparation of a number of heterocyclic sulfonyl chloride compounds (chlorosulfonyl substituted heterocycle compounds) from di(heterocyclyl) disulfide compounds (dithiobis(heterocycle) compounds) by reaction with chlorine in an aqueous acidic medium, a process type generally known as chloroxidation, has been disclosed in the art, for example, in U.S. Pat. Nos. 5,008,396 and 5,488,109. The disclosed chloroxidation procedures, however, give poor results when applied to the preparation of many heterocyclic sulfonyl chloride compounds from corresponding di(heterocyclyl) disulfide compounds. Low yields, for example, are typically observed in the preparation of heterocyclic sulfonyl chloride compounds from di(heterocyclyl) disulfide compounds that have little solubility in the reaction medium employed or that have other substituents that are reactive under the process conditions required. The discovery of a high yield process for converting a broad range of di(heterocyclyl) disulfide compounds to heterocyclic sulfonyl chloride compounds would be highly desirable.